Apparatus for molding plastic containers

ABSTRACT

An apparatus for blow molding hollow, thermoplastic containers having cylindrical neck openings. A blow pin assembly is provided which includes a cylindrical, retractable blow pin having an annular shoulder with a sharp edge adjacent its outer end which engages an anvil surface carried by the blow mold to sever the neck waste from the plastic container. An annular groove is provided adjacent the cutting edge of the blow pin, which groove is filled by the heat-softened plastic material and, after cooling, provides a firm connection between the blow pin and the neck waste to assure that the neck waste material is severed and carried away from the plastic article upon retraction of the blow pin.

United States Patent Hafele et al.

[ Aug. 14, 1973 1 APPARATUS FOR MOLDING PLASTIC CONTAINERS [75]inventors: Robert X. Hafele; Elmer L.

Robertson, both of Overland Park, Kans.

[73] Assignee: Ethyl Development Corporation,

Kansas City, Mo.

[22] Filed: Apr. 5, 1971 [21 Appll No.: 130,911

[52] US. Cl. 425/302 B, 264/94, 425/387 13 [51] Int. Cl. 829d 23/03 [58]Field of Search 425/326 B, 387 B; 264/94, DIG. 18

[56] 1 References Cited UNITED STATES PATENTS 3,025,562 3/1962 Nelson425/387 B X R24,577 12/1958 Haines 425/326 B X 3,632,261. 1/1972 Gasior425/387 8 X 3,531,556 Mehnert; 425/326 B X 3,029,467 4/1962 Nelson425/326 B X Primary Examiner-H. A. Kilby, Jr. Attorney-Donald L.Johnson, John F. Sieberth, 15. Donald Mays and Arthur G. Connolly [5 7]7 ABSTRACT An apparatus for blow molding hollow, thermoplasticcontainers having cylindrical neck openings. A blow pin assembly isprovided which includes a cylindrical, retractable blow pin having anannular shoulder with a sharp edge adjacent its outer end which engagesan anvil surface carried by the blow mold to sever the neck waste fromthe plastic container. An annular groove is provided adjacent thecutting edge of the blow pin, which groove is filled by theheat-softened plastic material and, after cooling, provides a firmconnection between the blow pin and the neck waste to assure that theneck waste material is severed and carried away from the plastic articleupon retraction of the blow pin.

9 Claims, 5 Drawing Figures Patented Aug. 14, 1973 5 Sheets-Sheet lPatented Aug. 14, 1973 3 Sheets-Sheet 2 ])I nl ill 59 57 FIG.

ullloll |l||| IIIIII FIG;

Patented Aug. 14,1973 I 3,752,628

3 Sheets-Sheet :5

APPARATUS FOR MOLDING PIJASTIC CONTAINERS BACKGROUND OF THE INVENTION 1.Field of the Invention This invention relates to a blow moldingapparatus having a blow pin assembly adapted to remove the neck wastefrom a blow molded, hollow container.

2. Description of the Prior Art Numerous techniques have been proposed.and utilized for removal of the neck waste normally present in a blowmolded container formed from a hollow, thermoplastic parison. Priorcommercial methods utilized a coring and trimming operation performedsubsequent to the formation of the hollow container in the blow mold.These prior art methods and apparatuses required the additional handlingof the bottles, the investment and operating cost for coring andtrimming machines, and the employment of additional operators, all ofwhich added to the cost of the blow molded container.

Many methods and apparatuses for in mold neck finishing of blow moldedcontainers have been-proposed. In U. S. Pat. No. 2,984,865 the neckwaste or moil is severed from the blow molded plastic article while thearticle is retained within the blow mold. A reciprocating blow pincarries a rotating sleeve which engages an outwardly extending,circular, severing edge formed adjacent the neck opening in the blowmold. Contact between the sleeve and the circular, severing edge cutsthe neck waste from the container. The circular sleeve is provided withserations adjacent its edge which engage the neck moil and, uponrotation of the sleeve, complete the separation of the moil from thebottle neck. In the commerical versions of blow molding apparatusesutilizing a serated, rotatable sleeve for breaking the neck mold fromthe neck of the container, problems have been encountered caused by thefilling of the serations with bits of plastic, thus rendering themineffective to grip and rotate the neck moil to shear it from the top ofthe container neck. The moil remains attached to the neck and must beremoved by a hand operation.

Other methods and apparatuses for severing neck waste from containershaving necks wherein annular knife or cutting edges extend inwardly fromthe walls of the blow mold within the neck opening are shown in U. S.Pat. Nos. 3,031,718; 3,363,282; and 3,487,501. In U. S. Pat. No.3,031,718 the neck mold insert is rotated to shear both the neck wasteand the edge flash from the container neck. This requires the use of acomplicated construction for the neck insert in addition to theneck-actuating device. In U.S. Pat. No. 3,363,282 a portion of the neckmold is longitudinally reciprocable whereby it severs and pushes theneck moil or waste down the blow pin, thus separating it from theplastic container to provide a finished neck. A complex apparatus isrequired toremove the neck flash according to the teachings of thispatent. In U.S. Pat. No. 3,487,501 a rotatable blow pin is providedwhich carries serations in a portion of its outer surface which engagethe moil or waste portion desired to be severed from the neck. Knivesare carried by the mold and partially sever the moil or neck waste fromthe container neck. The serations can become filled with bits of plasticwhich decrease the capability of the rotating tively severed from theneck and removed therefrom by withdrawal of the blow pin. The method andapparatus of the present invention provides for the positive severanceand removal of the plastic moil from the neck. of a blow molded plasticcontainer.

SUMMARY OF THE INVENTION It is an object of the present invention toprovide a process and apparatus for producing blow molded plasticcontainers.

It is a further object of the present invention to provide a process andapparatus for efficiently and economically finishing theneck ofa blowmolded container while the container is retained within the blow mold.

It is also an object of the present invention to provide a process andapparatus for positively severing and removing the waste portion fromthe neck of a blow molded container.

It is still another object of the present invention to provide a processand apparatus which is capable of producing a variety of difierent sizesof blow molded plastic containers having finished necks.

The apparatus aspects of the invention may be carried out in a blowmolding apparatus for producing hollow, plastic containers with neckswherein the combination inludes a pair of blow mold halves, each ofwhich is provided with a neck-forming means defining,

when closed, a generally cylindrical opening at one end thereof, theopening terminating in an .arcuately shaped, outwardly inclined,terminal wall portion. A blow pin is provided that is adapted to beinserted into the neck opening. The blow pin is provided with a shoulderhaving a sharp edge adjacent one end, which shoulder is slightly largerthan the opening and is adapted to seat on the terminal wall portion tosever or partially sever the excess plastic material from the neck. Theblow pin is provided with an annular groove adjacent the sharp edgedshoulder adapted to receive some of the excess plastic material and toretain the plastic material on the blow pin when the blow pin is removedfrom the opening. A hollow stripper sleeve slidably receives the blowpin and is adapted to strip the excess plastic material therefrom whenthe blow pin end is retracted into the stripper sleeve.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an elevational view,partially in section, of

an assembly for blow molding hollow containers coni structed inaccordance with the present invention;

FIG. 2 is an enlarged, elevational, partially sectional view of the blowpin and stripper sleeve of the apparatus of FIG. 1;

FIG. 3 is a view similar to FIG. 2 showing the blow pin retracted withinthe stripper sleeve and the removal of the plastic moil therefrom;

FIG. 4 is an enlarged, elevational, sectional view of a portion of theapparatus of FIG. 1 showing severing of the plastic moil from the neckof the container; and

FIG. 5 is a bottom plan view of the apparatus of FIG. 4 taken along theline 5-5 with the blow pin and plastic moil removed for a clearershowing of the anvil construction.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, theblow molding apparatus of the present invention includes a blowassembly, designated generally by the numeral 10. The assembly isattached to mounting brackets 11, which brackets are,

in turn, movably attached to the supporting frame for the blow moldingmachine (not shown). Top plate 12 is fixedly attached to the brackets 11and provides a central opening 13 therein. The blow assembly is providedwith a fixed collar 14 which rests on top plate 12 with the lowerportion of the blow assembly extending through the opening 13. Theunitary blow assembly 10 is movably attached to top plate 12 by means ofL- shaped brackets 15 having their lower ends attached to top plate 12.Thrust screws 16 are threadably received in brackets 15 and have theirinner ends in abutment with the side of collar 14. By adjusting thrustscrews 16, the position of the blow assembly can be altered to provideexact centering of the device in relation to the blow mold ashereinafter described.

A double-acting, hydraulic or pneumatic piston assembly, designatedgenerally by the numeral 17, extends downwardly from the top plate 12.The doubleacting piston assembly includes a cylindrical case 18 havingclosures 19 on each end thereof. The closures are provided with centralopenings (not shown) through which extends the piston rod 20. Packinggland 21 is provided on the lower end of the cylinder and seals thelower end of the piston rod 20 which extends therethrough. The lower endof the piston rod is provided with threads 22 and has a height-adjustingcollar 23 threadably received thereon. A stop nut 24 abuts theheight-adjusting collar and locks it in the desired position. Piston rod20 has affixed to its mid-portion a piston 25. Conduits 26 and 27 areprovided at the lower and upper end, respectively, of the pistonassembly whereby hydraulic fluid or air may be supplied to the interiorof case 18 on either side of the piston 25. Suitable means for supplyinghydraulic or pneumatic pressure through these conduits is providedwhereby piston may be moved upwardly or downwardly in case 18 asrequired. A generally cylindrical stripper tube 28 is attached to theupper surface of collar 14 by means of flange 29. The flange 29 may befixedly attached to plate 14 by welding or, if desired, removablyattached by means of bolts (not shown). Referring now to FIG. 2, theupper end of the stripper tube 28 is counterbored to provide acylindrical shoulder 30. A-cylindrical stripper sleeve 31 is slidablyreceived in the counterbore and has its lower end in abutment with theshoulder 30. Referring now to FIG. 1, the stripper sleeve surrounds theblow pin assembly, designated generally by the numeral 32, which has itslower end threadably attached to the upper end of piston rod 20. Theblow pin 32 is axially slidable and maintains a close fit with thestripper sleeve 31 to insure exact alignment of the blow pin with theblow mold. Stripper tube 28 is provided with a plurality of longitudinalslots 33 through which extend service conduits. Conduit 34 suppliesblowing air for inflation of the plastic article. This conduit connectswith a supply conduit (not shown) contained within the hollow body 35 ofthe blow pin assembly. Conduit 36 is the inlet supply line for coolingwater to the hollow body 35. Conduit 37 is the exit line for coolingwater. Conduit 38 supplies carbon dioxide which, if desired, may be usedfor cooling the blow molded plastic container. Nozzle 39 is positionedopposite the upper end of the blow assembly and is adapted to supply anair jet to remove the neck flash or moil as will be subsequentlydescribed.

As seen in FIGS. 1 and 4, a blow mold having partable halves 40 and 41is positioned above the blow assembly 10 and is adapted to be engaged bythe upper end of the blow pin assembly 32. The mold halves 40 and 41 areopened and closed by conventional pneumatic or hydraulic means (notshown). As seen more clearly in FIGS. 4 and 5, the mold halves areprovided with halves 42 and 43 of an annular split anvil. These anvilsare received in a counterbored, circular recess 44 provided in the lowerface 45 of the blow mold halves. Cap screws 46 retain the anvil halvesin place. Each anvil half is provided with a sloped inner wall 47. Theupper end of the blow pin assembly is provided with a removable tip 48which may be threadably received on the end of the blow pin assembly.The tip 48 is provided with upwardly tapered sidewalls whereby it willbe received within the neck 49 of a plastic bottle 50, which is, inturn, contained within the cavity 51 provided by the blow mold halves 40and 41. While the tip, as shown in the exemplary drawings, only contactslightly the upper end 52 of the neck 49, if desired, the tip may beshaped whereby sliding contact is made between the tip and the neck ofthe container 49 over a substantial portion of its length. Thus, thethreads 53 can be formed on container neck 49 by virtue of the flow ofsoftened plastic material into thread recesses 54 provided in the blowmold halves, which flow is produced by either air pressure applied inblowing the container or by the contact from the blow tip 48.

Immediately below the blow tip 48 there is provided an annular cuttingsleeve 55 slidably received over the reduced end of the hollow body 35of the blow pin assembly. As seen more clearly in FIGS. 2, 3 and 4, thecutting sleeve is provided with a sharp, circular cutting edge 56 ateach end thereof. Immediately below each cutting edge an annular recess57 is provided in the outer wall of teh cutting sleeve 55.

In operation, the blow molding apparatus of the present inventionreceives a conventional plastic parison or hollow tube which is extendeddownwardly through the open halves of the blow mold 40 and 41.Conventional means close the mold halves and seal the bottom (not shown)of the plastic bottle 50. The lower end 58 of the parison extendsthrough the neck opening provided in the mold halves. The hydraulicpiston assembly is actuated moving the blow pin assembly 32 upwardly andinto the lower end of the parison 58 flaring it in the manner depictedin the drawing. The tip 48 moves into the neck opening, and the circularcutting edge 56 of sleeve 55 presses against the inclined surface 47 ofanvil halves 42 and 43 either partially or completely severing the neckmoil" or waste portion of the lower end of the parison 58 from the neck49 of the plastic bottle. Since the neck moil 58 is still warm andthermoplastic, an annular bead 59 is formed on the inner wall of moil 58and is received within the annular recess -57 provided at the upper endof the cutting sleeve 55. As chilled water flows through the blow pinassembly 32, the moil 58 is cooled and the annular bead 59 becomes rigidand firmly seated in the recess 57.

After the cooling cycle for the bottle is completed, the hydrauliccylinder is reversed to retract the blow pin assembly 32 downwardly intothe stripper tube 28. As can be seen in FIG. 2, th tight fit ofthe beadS9 in recess 57 firmly attaches th moil 58 to the end of the blow pinassembly. Upon further retraction of the blow pin body 35, the cuttersleeve and the tip are drawn into the interior of the stripper sleeve 28as seen in FIG. 3. In this step the lower end of the moil 58 contactsthe top of either the stripper tube 28 or the stripper sleeve 31 and isstripped out of the groove 57 to remove the moil from the end of theblow pin. A pulse of air is then supplied through nozzle 39 whichremoves the moil 58 from the top of the stripper assembly therebyreadying the blow pin assembly for the next cycle.

Thus, it can be seen from the foregoing that the apparatus of thepresent invention provides a novel and efficient means for blowing aplastic bottle and simultaneously finishing in the mold the neck of thebottle without further operations being required. While the apparatushas been depicted and described in conjunc' tion with a blow moldingapparatus wherein th blow pin is inserted in the bottom of the blowmold, it is to be understood that the invention is equally suitable inblow molding apparatuses wherein the blow pin is inserted into the topof the blow mold. While there has been described what is at presentconsidered preferred embodiments of the present invention, it will beapparent to those skilled in the art that various modifications andchanges may be made without departing from the essence of the invention.It is intended to cover herein all such modifications as come within thetrue spirit and scope of the following claims.

What is claimed is:.

1. In a blow molding apparatus the combination comprising:

a. a double-acting, fluid-actuated power assembly having an axiallyaligned, reciprocable rod extending from one end thereof;

b. a hollow stripper tube attached to said power assembly at said oneend, said tube surrounding and being axially aligned with and spacedfrom said rod;

'c. a blow pin assembly surrounded by and spaced from said tube andhaving one end attached to said rod whereby its other end is movableinto and out of the open end of said stripper tube; and

d. a removable generally cylindrical stripper sleeve received in theouter end of said sleeve surrounding and in slidable contact with aportion of said blow pin assembly.

2. In the apparatus of claim 1 wherein said tube is provided with aplurality of longitudinally extending slots adapted to receive connectormeans for supplying said cooling fluid and blowing gas: to said blow pinas- 5 sembly.

3. In the apparatus of claim 1 including means to sup port thecomponents set forth in subparagraphs a) through d) of claim 1, saidsupport means including means to change the axial position of saidcomponents.

4. In the apparatus of claim 1 wherein said stripper sleeve is seated ona shoulder provided on the interior wall of said stripper tube and saidblow pin assembly is removably attached to said one end of said rod.

5. In a blow molding apparatus for producing hollow plastic articleswith necks, the combination comprising:

a. a pair of blow mold halves, each of which is provided withneck-forming means defining, when closed, a generally cylindricalopening at one end thereof, said opening terminating in an conicallyshaped, outwardly inclined, terminal wall portion;

b. a blow pin adapted to be inserted in said opening, i. said blow pinproviding a flat shoulder having a sharp edge adjacent one end, whichshoulder is slightly larger than said opening and is adapted to seat onsaid terminal wall portion to sever or partially sever the excessplastic material from said neck,

ii. said blow pin providing an annular groove adjacent and rearwardly ofsaid sharp edged shoulder adapted to receive some of said excess plasticmaterial and to retain said excess plastic material on said blow pinwhen said pin is removed from said opening; and

c. a hollow stripper sleeve slidably receiving said blow pin and adaptedto strip said excess plastic material therefrom when said one end isretracted into said stripper sleeve.

6. In the apparatus of claim 5 wherein said sharp edged, flat shoulderis provided on a separable cutter sleeve carried by said blow pin.

7. In the apparatus of claim 5 wherein said neckforming means includes apair of neck insert halves removably attached to said blow mold halves.

8. In the apparatus of claim 6 wherein said cutter sleeve is providedwith a sharp edged, flat shoulder adjacent each end thereof.

9. In the apparatus of claim 7 including a pair of anvils removablyattached to said neck insert halves to provide said conically shaped,outwardly inclined, terminal wall portion of said cylindrical opening.

1. In a blow molding apparatus the combination comprising: a. adouble-acting, fluid-actuated power assembly having an axially aligned,reciprocable rod extending from one end thereof; b. a hollow strippertube attached to said power assembly at said one end, said tubesurrounding and being axially aligned with and spaced from said rod; c.a blow pin assembly surrounded by and spaced from said tube and havingone end attached to said rod whereby its other end is movable into andout of the open end of said stripper tube; and d. a removable generallycylindrical stripper sleeve received in the outer end of said sleevesurrounding and in slidable contact with a portion of said blow pinassembly.
 2. In the apparatus of claim 1 wherein said tube is providedwith a plurality of longitudinally extending slots adapted to receiveconnector means for supplying said cooling fluid and blowing gas to saidblow pin assembly.
 3. In the apparatus of claim 1 including means tosupport the components set forth in subparagraphs a) through d) of claim1, said support means including means to change the axial position ofsaid components.
 4. In the apparatus of claim 1 wherein said strippersleeve is seated on a shoulder provided on the interior wall of saidstripper tube and said blow pin assembly is removably attached to saidone end of said rod.
 5. In a blow molding apparatus for producing hollowplastic articles with necks, the combination comprising: a. a pair ofblow mold halves, each of which is provided with neck-forming meansdefining, when closed, a generally cylindrical opening at one endthereof, said opening terminating in an conically shaped, outwardlyinclined, terminal wall portion; b. a blow pin adapted to be inserted insaid opening, i. said blow pin providing a flat shoulder having a sharpedge adjacent one end, which shoulder is slightly larger than saidopening and is adapted to seat on said terminal wall portion to sever orpartially sever the excess plastic material from said neck, ii. saidblow pin providing an annular groove adjacent and rearwardly of saidsharp edged shoulder adapted to receive some of said excess plasticmaterial and to retain said excess plastic material on said blow pinwhen said pin is removed from said opening; and c. a hollow strippersleeve slidably receiving said blow pin and adapted to strip said excessplastic material therefrom when said one end is retracted into saidstripper sleeve.
 6. In the apparatus of claim 5 wherein said sharpedged, flat shoulder is provided on a separable cutter sleeve carried bysaid blow pin.
 7. In the apparatus of claim 5 wherein said neck-formingmeans includes a pair of neck insert halves removably attached to saidblow mold halves.
 8. In the apparatus of claim 6 wherein said cuttersleeve is provided with a sharp edged, flat shoulder adjacent each endthereof.
 9. In the apparatus of claim 7 including a pair of anvilsremovably attached to said neck insert halves to provide said conicallyshaped, outwardly inclined, terminal wall portion of said cylindricalopening.